In recent years, moving image distribution services such as YouTube have enabled a large number of people to easily view various moving images on the Internet. By widely requesting general users to create content of moving images or the like, these moving image distribution services rely on the users to create and provide various content items. Receiving these various content items from the users, the moving image distribution services store the content items into moving image distribution servers to distribute the content items to an unspecified number of users. Then, a user as a viewer uses a function of searching by keywords to find a content item that the user is interested in, and then can view the content item in a streaming format.